Several systems for scoring simulated weapons fire have heretofore been proposed wherein a beam of radiation was used to simulate a projectile fired from the barrel of a weapon and wherein aiming of the weapon was scored on the basis of whether or not the beam was detected either by a detector located at the target or by a detector located at the weapon position and towards which the beam could be reflected by a retroreflector on the target.
Any such system must take account of the fact that a real projectile follows a curving track and takes a substantial amount of time to move from the weapon position to the target area, whereas a beam of radiation follows a straight path and moves from the weapon position to the target area in an extremely short period of time.
U.S. Pat. No. 3,609,883 disclosed a system wherein, at the instant of simulated firing of the weapon, a calculation was begun, based upon the superelevation of the weapon barrel at that instant, of the trajectory that would have been followed by a real projectile fired from the weapon at that instant. In accordance with that calculation, the axis of a laser emitter was depressed relative to the orientation of the weapon barrel axis at the firing instant, and after a time interval equal to the calculated projectile flight, a narrow beam of radiation was emitted towards the calculated point at which the imaginary projectile was assumed to have terminated its flight. A hit or miss was scored on the basis of whether or not the beam fell upon a detector at the target.
One disadvantage of that system was that it required the use of some means independent of the laser apparatus for measuring range distance between the weapon and the target. A more important disadvantage was that the system could not register anything but a miss if the laser beam did not strike a radiation detector--even when the beam missed the detector by a distance so small as to be practically insignificant. For anything other than hit-or-miss scoring, the target body would have had to be literally covered with detectors; and even with that costly arrangement, near misses could not have been scored for simulated shots falling just outside the limits of the target body. For effective training accurate scoring of near misses is important because only from such scoring can the gunner learn what kind of errors he is making.
U.S. Pat. No. 3,588,108 disclosed a simulated weapons fire system wherein a laser beam was moved in an area-search type of scanning sweep at the time of termination of the calculated trajectory of an imaginary projectile, and was modulated at different frequencies in different sectors of the area swept during its scan,. On the basis of the modulation frequency impressed upon a detector at the target by the sweeping beam, accuracy of aim could be scored in terms of near misses as well as direct hits and complete misses. The field of scan of the sweeping laser beam had to be large enough so that two or more targets might intercept it if they were relatively close to one another, with consequently inaccurate and confusing scoring results, and therefore the system could be used only with simulations of limited tactical situations. The system tended to be inaccurate with moving targets, and it required signaling means or a special transmitter at each target for transmitting scoring information back to the weapon location.
U.S. Pat. No. 3,832,791 disclosed a gunnery training scoring system wherein a first radiation emission at the instant of simulated firing was employed for ranging, to ascertain the duration of the time interval theoretically required for a round of a selected type of ammunition to arrive at the detected position of the target; and at the end of that interval a second emission was used to obtain a fix on the target and to transmit information to the target concerning ammunition type and the point of impact of the simulated projectile in relation to the then-existing position of the target. Such information was encoded in modulation of the beam and was decoded at the target to be used for evaluating hit effect. The beam in that case was a substantially divergent one, having an angular height equal to the angle through which the weapon barrel could be swung in elevation and a width to cover an entire target body at minimum shooting distance. By reason of this diffusion, only a small portion of the total emitted radiation could reach any particular detector in the system, and therefore received signal strength was relatively low and there was a correspondingly low ratio of signal to background disturbance.
In common with the system of U.S. Pat. No. 3,588,108, the last described system had the further and more serious objection that if there were, for example, two targets within the relatively wide space illuminated by the beam, both at about the same distance from the weapon location and each denoted by a reflector and an adjacent detector, both detectors would receive information encoded in the beam, even though the information was valid for only one of them.
The above mentioned technical disadvantages of the respective prior scoring systems generally resulted in inaccurate scoring, at least under cetain conditions, and also tended to impose limitations upon each such system with respect to the simulated tactical situations in which it could be used effectively.
The general object of the present invention is to provide a scoring system for simulated weapons fire that overcomes or avoids the technical disadvantages possessed by prior systems and is, in addition, much more versatile, being capable not only of simple hit-or-miss scoring but also of accurate hit effect scoring in realistically simulated complex tactical situations. With respect to versatility, it will have been observed that each of the above described prior systems required the presence of a detector at the target, along with receiving equipment associated with the detector. By contrast, the system of the present invention operates in one mode wherein the target need only be equipped with a reflector by which radiation from the weapon location is reflected back to that location, so that scoring can be effected there, but has another mode of operation in which the target is equipped with a detector in addition to the reflector and in which calculation is made at the target body of the hit effect upon the target body that has been achieved with each simulated shot. Thus, in contrast to prior scoring systems, each of which usually had only one mode of operation, apparatus embodying the principles of this invention can be of a rather simple type for basic target practice work and can be elaborated, building-block fashion, to accommodate itself to increasing sophisticated scoring of increasingly complex simulated tactical situations, in accordance with training requirements and budget limitations.
The present invention contemplates the employment of modulated, fan-shaped beams of radiation, swept flatwise angularly, in connection with a system for scoring of simulated weapon fire. With respect to the employment of such beams in certain modes of operation of the system of this invention and under certain conditions, the present disclosure is supplemented by my copending applications Ser. No. 14,117 and Ser. No. 14,116.
Ser. No. 14,117 discloses a method and apparatus for employing such sweeping beams to determine the positions of each of a plurality of targets in a space swept by the beams, wherein there is no presentation of spurious target positions such as occurred with prior systems using angularly sweeping fan-shaped beams when multiple targets were present in the swept space. My other copending application, Ser. No. 14,116, discloses a method and apparatus for causing information transmitted by modulation of such beams to be delivered exclusively to such of the targets in the swept space as are at a predetermined distance, or at predetermined distances, from the location from which the beams are emitted.
Heretofore in weapons practice systems in which radiation from a laser or the like has been employed, the laser radiation has been used to simulate the projectile fired at the target. Thus the beam of radiation was emitted at the time following the firing instant when a real projectile, had it been fired at that time, would have arrived at the target; and the beam was so directed that it intersected the point in space at which the real projectile would have arrived at the end of its time of flight. It is obvious that fan-shaped, flatwise-swept beams cannot be employed in that manner. But it has not been obvious how fan-shaped sweeping beams can be employed in such a training system, and in fact it has not heretofore been evident that there would be any advantage in the use of such beams, even assuming that there was a solution to the problems heretofore recognized as inherent in their use.
Nevertheless, the general object of the present invention is to provide a method and apparatus for the scoring of simulated weapon fire which is both more accurate and more versatile than simulated weapons fire scoring systems heretofore known, and which employs fan-shaped beams of radiation that are angularly swept flatwise.
With respect to accuracy, it is an object of this invention to provide a method and apparatus that makes possible the accurate scoring of simulated weapon fire on the basis of hit effect, that is, on the basis of the amount and kind of damage that would have been inflicted upon a predetermined target body by a real projectile of a predetermined type if it had been fired by the gunner under all of the relevant conditions that existed at the instant of simulated firing.
With respect to versatility, it is an object of this invention to provide for accurate scoring of simulated firing at either fixed or moving targets, from a stationary or a mobile weapon position, with a slow-firing or a rapid-firing weapon, and with ballistic, self-propelled, guided or unguided projectiles, and to enable such scoring to be accomplished with great accuracy at the weapon location and/or at a target position. It is also an object of the invention to provide such a scoring system which is versatile enough to be readily adaptable for use in simulated land warfare or sea warfare and in simulated ground-to-air, air-to-ground and air-to-air operations.
A further and very important object of this invention is to provide a system for scoring of simulated weapons fire wherein laser radiation is emitted from the weapon location but wherein each target need only comprise a retroreflector, no radiation detector being needed at the target to enable the gunner to obtain prompt and useful information at the weapon location about the results achieved with each simulated shot.
It is also an object of the invention to provide a simulated weapons fire scoring system that affords accurate scoring of near misses as well as hits, enables a prompt evaluation to be made of the hit effect achieved with each simulated shot, and provides for prompt display of scoring results at the weapon location and/or at all target locations or only at such target locations as are of interest.